In the 40 years since Stanford and Yale undertook the first large scale preservation assessments of library collections, American library collections and responsibilities have grown dramatically, even as funding has failed to keep pace. Evaluating the condition and needs of collections remains essential to preserving collections for current and future users and allows librarians to direct their limited resources towards areas of the most meaningful impact. This chapter will examine the four primary types of preservation assessments undertaken in libraries and archives: Preservation Needs Assessments, Collection Condition Surveys, Collection Assessments, and Item-Level Condition Reports. Each type of assessment offers distinct ways to understand, and benefit, collections and repositories. The focus of this chapter will be on outlining goals and benefits for each assessment format, as well as how to structure the assessments efficiently to provide actionable results.